Gravitation measuring instrument



Jam ll, 1938. H. HAALCK GRAVITATION wnzAsuRINcsfV INSTRUMENT Film1 July 1o, 195e M m w .A M w w y Affe/wey exploration work, variations inv the structure of the earths crust by malnng comparative measure- Patented 1,938

PATE

GitAvrrATroN MEASURING INSTRUMENT Hans Haalck, Potsdam, `Germany, ,assignor to Askania-Werke A. (i. 4vormals Oentralwerkstatt-Dessau und Carl'Bamberg-lriedenam a corporation 'of Germany Application July' 16,. 1936, sei-n1 No. '90,036

In Germanynprn 1, 1935 s alms.r (c1. 26e-'1.4)

My invention relates'to the art of detecting in connectionl with surveying and geophysical ments of the force vof gravity, designated by Physicists bythe symbol g and for, convenience sake called gravity-constan the problem being to actually measure those very while intrusion of a relatively. light mass at aparticular point ielow the earths surface tend to decrease the value of "g at' that point. 'I'hese facts have been relied-on as an aid to the locationof hidden deposits of various kinds, such as salt, ores, oil etc., and exploration methods based thereon are particularly well suited to regions where definite variations of the value of g may y be taken to Vindicate-'with fair certainity a particular geotectonic formaidon.-

y It has been vdiscovered that certain deviations in the positive sense of the value of g from the l normalY value to` be expected at the particular places under observation constitute a reliable indication, for instance, 'of the presence of a salt dome.- This, in turn, is often indicative of 'a structure containing an accumulation 4of oil;

Various measuring 'methods and' I instruments based on geodynamic, static, magnetic, barometric f and seismographical principles have been suggested for determining the' variations of the fac torgl or its relative value, over large areas. Diiiiculties however have been vexperienced in many casesin adapting the gravity testing instrument to extensive exploration work because oi' the great care 'and precision required in setting f up the instrument, the length of time required for reaching the state of equilibrium of forces fand obtaining the appropriate readings, the high cost of the instrument and its delicate design, which calls for ,highly trained operators and cautiousl treatment, land which renders it diiilcult to transport thev measuring instrument into relatively in` A accessible locations, and to the slowness of the measuring operations in general.

'I'he principal iobject' oi this invention 'is to overcome, the said drawbacks by providing a.l gravitational measiuing o'r testing instrument vof simple design and involving simple barometric principles, on which g existing at various exploration points canbe read wit-h ease on,` a; relatively large scale and without loss of time. l

NT orifice. i.

the diierences inthe factor -v Another equally important object ofthe lnven- 5 i y tion consists inprovidin'g a barometric measuring instrument distinguished by its' higher sensitiveness to variations of the value g than that n I of instruments of the same type known heretofre,-which y to onetenth of 'a milligal, a unit ofmeasurement recently adopted by scientists and practitioners inthisfield.' I y f Other objects of the invention will incidentally' become evident hereinafter to thosefamiliar wishk 15` the making of gravity measuringinstruments of this class andexploration work to be carried out p therewith.` f y The nature and scope of the invention ar briefly outlined in the appended claims and will be more fullyunderstood from ther'following speciication taken togetherY with the' accompanying ments of this invention.

Fig. 1 isv a layout diagrammauanyshowing 25 gravitational measuring `instrument designed'according tothis invention.. Fig.- 2 vshows a structurally modiiied` instru- Fig. 3,is .a cross section taken through a box 30` containing`a liquid, wherein two/measuring instruments designed according invention are immersed. i i

Briefly stated the invention 'consists in cowill indicate gravity differences down 10 operatively interconnecting in series two baro-"35 vmetric tubes containing mercury columns by an intermediary tube; keeping'in equilibrium said mercury columns by associating their `respective upper 'and lower levelswithv.iiuids,fwhich areunder different pressure' and are sealedin vessels 4'0 from the atmosphere, and providing means associated with said intermediary tube and mercury columns for indicating Achanges of the force of 1 gravitation reacting upon said mercury columns.

In the embodiment of the invention', shown by 45 way `of an example iiiFig. 1, the gravitational measuring instrument tco'mprises two vertical tubes a and a' connected at their'lqwer and upper `lends, respectively, to pairs of ,qseald'vessels or drawing-showing for illustrative purposesl embodi- 1 @1 containers 0,122 and v3, v4 and' mercury clunmsqo t m and ml" in the" tubes partially'liill theV upe andlower vessels. An intermediary tubeA desig-F y nated i, i', interconnects in sexies thejtubes ma' by putting intocommunication the upper vesseli lv2 with `the 'lower-vessel vs, rimas, for instance ail al miles distantvfrom the base A, where theincomprise an U-shaped tube p, p of glass or other translucent material containing a. column of a coloured liquid, for instance glycerine, and scales c, c' the graduations of which register with the ascending and descending meniscus of said liquid column.

Damping or baiiiing means may be provided to advantage in said U-shaped tube p, p' with thel object of `preventing undue oscillations of the liquid column, which accidentally occur and would impair the speedy reading ofthe scales c, c'. In the embodiment of the invention shown in Fig. l said damping means comprises a valve or cock f provided in the lower section of tube p, p' adapted to oier frictional resistance to the liquid passing therethrough. Another valve or oockj connects the tubes i, i', so that on closing or opening cock f' the by-pass or U-shaped tube 11, p' is in or out of operation. i

Means provided forV protecting the measuringinstrument against anychanges o! temperature even the slightest are illustrated in Fig. 3. This iigure shows an outer casing b having double walls of insulating material and being so proportioned,

that two gravitation measuring instruments of the modified design shown in'Fig. 2 and described hereinafter can be inclosed therein together with inner casngs b carrying the instruments proper. Windows w, w' are 'provided in said box for the admission of light and for' rendering visible to the operators the gravitational indicating means of the instruments, which are shown in this instance as being arranged between the containers b' and the inner walls of the box b'.' lThe space within and around the casings l'- may be filled with'ice water or water and cracked ice to maintain the temperature at approximately the melting point of ice. The ice water maintains the temperature of the instruments within the, containers substantially constant and the insulated walls of the box prevent the ice from melting too rapidly. 1

Theoperation of the instrument is as follows: v i

I which ingalignment vessels v8, v1, p6, vi are mounted with respect to the vertical axis. The 50 It may be assumed.v that a series of measurementsis to be made, beginning at a point B severstrument is located.`and where the operatoris Y about to start from on his exploring expedition.

Beforeleaving the base A the operator should first fill the casings containing the instruments with cracked ice or with water of melting temperature having pieces of ice noating thereon,

so as to keep the temperature constant at aero around the merclny tubes for a considerable length of time. Blight changes in temperature,

which accidentally might occur in the water of the I outer casing cannot pervade the insulating walls b' and will not affect the 'temperature of the water inside the walls b and around the instruments proper.

At the base A the zero point of the instrument is adjusted by opening thecock f' and thereby equalizing the pressure in vessels v2 andv. .After the adjustment the cock f' is closed and the instrument is ready for a measurement ata point B.

Inorder to eliminate undue oscillations of the liquid column in thetubes p, p' the cock l' may be so adjusted as to onerconsiderable' ilow resistat point B is greater than at A: In -this case both mercury columns a, a' would have grown heavier during the travel of the instrument from A to B with the result, that the volume of gas contained in vessel v3, and in the intermediary tube i, and 5 p is proportionately expanded. f 10 Because of the combined forces of the com'' pressed and expanded gases in the tubes i' and i respectively reacting in the same direction upon the column of indicating liquid in the tubes p, p'

the indicating liquid will rise in tube p relatively l5 high. A considerable increase in range of travel of the indicating liquid, is obtained, as compared with other gravitation measuring instruments, wherein only one single barometric tube is employed, by providing a couple of barometric 'tubes 20 arranged in series for cooperation and combined action upon the indicating liquid. The readings or measurements taken in this manner at point B, and subsequently at other points during the exploring expedition indicate4 the extent of the 25 anomalies in gravity in the particular field, and thereby reflect variations in the subsurface struc- /tures with a high degree of accuracy.

yVarious other changes and modications may be conveniently made in the structural details of 30 gravitation measuring instruments of the improved design described, without substantially departing from the spirit and the salient ideas of this invention.

Extensive experimental work carried out by the 35 inventor with measuring instruments having two mercury columns cooperatively interconnected have revealed that the correctness of the measurements taken and the accuracy of the readings depend also on the form and arrangement of the 40 in symmetric position above each other as seen in 45 Fig. 2. l

In the embodiment shown in Fig.l 2 a support k of cork or other suitable material is shown on vessels v8 and v6 form an upper pair, while the vessels v1 and v5 form a lower pair spaced from the upper one in a vertical direction.

For increasing the volume ofthe lower vessel of one of the pairs, in the illustrated example, the 55' 'vessel 'v5 another vessel v5' is provided communieating with the vessel v5 and arranged preferably between the upper and the lower pair of vessels.

For compensating for temperature iniluenc a compensation vessel g is shown including a liquid q of relatively high thermal coeilicient of expansion. Upon a rise in temperature the liquid q will expand thereby decreasing the'volume of gas in' the vessel q and accordingly effecting a correction 0 of the indication.

For indicating the diierential premure between the lower of the first vessels .vl and v1 and the upper of vthe second vessels v6 and vla Z-shaped .tube Z is shown inclosing a mobile liquid'and cooperating with a scale. The arrangement of parts l 0 shown in this' embodiment offers the advantage of being, less responsive' to deviations of the instrument from the true vertical which in the embodiment of Fig. 1 would cause relatively greater error in the indication.

I Gf

scale or scales, is a function of the gravity force..-

Obviously, the invention is not limited to the I particular embodiments thereof herein shown and 15 Y y s l, l y

described.

What I claim is: y y 1. A gravity responsive inst ent comprising, in combination; two vertically spaced first vessels; a charge of'gas in'each rst vessel; a rstf conduit connecting said rst vessels; a rst mercury'column in said first conduit, vthereby tend-` ing to vary the expansion and compression of the gas in they upper and lower rst vessels. respectively, when the instrument is subjected to variations in gravitational force; two verticallyspaced second vessels; a charge oi gas in each second vessel, a second conduit connecting said second vessels; a second mercury column in said second conduit, thereby tending to vary the expansion and f compression of the -gas inthe upper and- -lower second vesselsrespectively, when the instrument is subjected to variations in gravitational force; and AVindicating means responsive t0 a pressure differential in the lower first and upper second vessel, the diii'erential pressure being a function of the gravitational force acting on said mercury columns. .r

2. A gravity responsive 'instrument comprising, in combination, two vertically spaced iirst vessels; a charge of gas in each rst vessel; a first Y conduit connecting said rst vessels; a irst mercury column in said iirst conduit, thereby tending to vary the expansion and compression of the gas in the .upper andtlower rstvessels, respectively, when the instrument is subjected to variations in-grav'itational force; two vertically spaced second vessels; aA charge of gas in each second vessel; a second conduit connecting said lsecond vessels; a secondmercury column in said second conduit, thereby tending to vary the expansion and compression vofthe gas in the upper and lower second vessels, respectively, when the in'- strument is subjected to variations in gravitational force; a U-,shaped tube communicating with said lower nrst and upper second vessels; and a'liquidin said tube which is thereby moved in response to a differential pressure in said lower first and upper second vessel, the diierential pressure being a function of the gravitational 'force acting on said mercury columns.

-3; A gravity responsive instrument comprising,

combination, two vertically spaced iirst vessels; a charge of gas in each rst vessel; a'rst conduitconnecting said first vessels; va irst mercury column in said rst conduit, thereby tend ing tovary the expansion and compression of the gas -in the upper and lower rst vessels, respectively,when the instrument is subjected to variations-in gravitational force; two -vertically spaced second vessels; a charge of gas in each second ves'- sel;'a second conduit connecting said second vessels ;v a second mercury column in said second conduit, thereby tending to vary the expansion and compression of the gas in the upper and lower second vessels, respectively, when'the instrument is subjected to variations in gravitational force;

a U-shaped tube commenting with said lower iirst and upper second vessel; a liquid in said tube which is thereby acted upon by a-pressure diierential in said lower iirst and upper second vessels; and means for dampening oscillations of said liquidin said tube. l

4. A gravity responsive instrument comprising, in combination, 'two vertically spaced first vessels; a charge of gas in each rst vessel; a first conduit lconnecting said iirst vessels; a firstmer- V cury column in said irstconduit, thereby tending to vary the expansion and compression of the gasin the upper and lower rst vessels, respec tively, when theinstrument is subjected' to variations in gravitational force; two vertically spaced second vessels; a charge of gas in each second vessel; a second conduit connecting said second vessels; a second mercury column in saidsecond conduit, thereby tending to vary vthe expansion and compression of the gas in the upper and lower second vessels, respectively,.when the ,in-

strument is subjected to variations in gravitational force; indicating means responsive to, a

pressure diierential in said lower iirst and upper second vessel; and means for by-passing "said, pressure responsive means to effect a zero adjust-v ment-of the instrument.

5. A gravity responsive instrument comprising, l

in combination, two vertically spaced irst ves'- sels :fa charge of gas 4in each rst vessel; a first conduit connecting said iirst vessels; a rst mercury column insaid iirst conduit, thereby tending to vary the expansion andv compression of the gas in the upper and lower first vessels, respectively, when t`he instrument is subjectedl to variations in gravitational force; two vertically spaced 'v second vessels; a charge of gasin each second vessel; a. `second conduit connecting said second vessels; a second mercury column in said .-second conduit, thereby tending to vary the expansion and compression of the gas in the upper and lowerA second vessels, respectively, when the' instrument is subjected to variations in gravitational force; .a U-sliaped tube 'communicating with said lower iirst and upper second vessels; a valve in said tube; a liquid in saidtube, the

liquid being thereby acted upon by Vajpressure diiferentialin said lower rst and upper second vessels; a by-pass conduit connecting said lower' first and upper second vessels; and a valve in said by-pass conduit. Y

6,. A gravity responsiver instrument ,compris-K' fing, in combinatiom two vvertically spaced iirst vessels; a charge ofgas in each iirst vessel; a .ilrst conduit connecting saidfirst vesselspa rst mercury column invsaid rst conduit, thereby tending to vary the expansion and compression of the gas inthe upper and lower rst vessels,

u, respectively, when the instrument is subjected to variations in gravitational force; two vertically spaced second vessels; a charge of gas in each second vessel; a second conduit connecting said second vessels; a second mercury column in said second conduit, thereby tending to vary the ex" pansion and compression of the gas in the upper and lower second vessels, respectively, when the instrument is subjected to variations in; gravitational force; a body of liquid arranged to lncrease and decrease the volume vof said upper rst vessel by thermal contraction and expansion to compensate for changes ln temperature affectlng the gas; and indicating means responsive to a pressure diierentialin the lower rst and upper second vessel, the differential pressure being a function of the gravitational lforce acting on said mercury columns.

7. A gravity responsive instrument comprising, in combination, two vertically spaced rst vessels; a charge of gas in each rst vessel; a rst Vconduit connecting said rst vessels; a rlrst mercury column in said rst conduit, thereby tending tovary the expansion and compression of the gas in the upper and lower rst vessels, respectively, when the instrument is subjected to variations in gravitational force; two vertically spaced second vessels, said first and .second vessels being aligned with respect to the vertical axis, whereby the upper and the lower vessels are positioned vertically adjacent to each other,"

forming pairs; a charge of gas in each second vessel; asecond conduit connecting said second vessels; a second mercury column in said second conduit, thereby tending to vary the expansion and compression of the gas .in the-upper and lower second vessels,vrespectively, when the instrument vis 'subjected to variations in gravitational force; a further vessel communicating with the lower vessel of one of said pairs; and indicating means responsive to a pressure differential in the lower first and upper .second vessel, the diierential pressure'being a function of the -gravitational force acting on said mercury columns.

8. A gravity responsive instrument comprising, in combination, two vertically spaced first vessels; a charge of gas in each rst vessel'; a

iirst conduit connecting said rst vessels; a'ilrst mercury column in said flrstvconduit, thereby tending to vary the expansion and cdinpression of the gas in the upper and lower first vessels, respectively, when the instrument is subjected to variations in gravitational force; two vertically spaced second vessels; a charge of gas in each second vessel; a second conduitconnecting said dow through winch said indicating meansvmay be observed; .and va illling of ice and 'water at melting temperature` in said outer and innercasing for maintaining )said vessels and conduits at an eventemperature. l

HANS HAALCK. 

